Abstract:

This study was carried out in the department of geotechnology at VR Track Ltd. Railway Consulting and funded by the Finnish Railroad Administration. It was supervised by specialists from VR Track Ltd. and the Finnish Railroad Administration. The purpose of this research was to examine embankment pile structures, i.e. both pile cap structures and pile plates. The opening chapter deals with embankment pile structures in general. Specific emphasis is paid to reconstruction and construction of embankment pile structures on operational railway tracks. Construction is much more challenging than usual in the difficult setting of an operational railway, as rail traffic imposes practical constraints on the progress of construction. Reorganisation of rail traffic may be expensive. The aim of this thesis was to compare different construction methods and evaluate the efficiency of each method in the setting of an operational railway. A further aim was to make suggestions for follow-up research.

The chosen method of study incorporates a literature review and interviews with specialists. The literature survey provides a general overview of embankment pile structures. Experienced engineers, builders and track maintenance personnel provided further in-depth information about construction methods. Some of the newest methods have not been put into practice yet, hence it was impossible to obtain reliable information on their efficacy and cost. The evaluation of the new methods is based on estimates made by experienced specialists.

The following observations were made: The best methods are those that cause minimum disturbance to rail traffic. Construction of a pile plate is the most reliable means of preventing the track settlement for decades. For most tracks in Finland, a traffic break of 6 hours can be managed at reasonable cost. Longer breaks require complicated and costly reorganisation of train timetables. The chosen method must suit the construction of the site in question. For example, in the case of the reconstruction of a bridge, which requires a break of 12 hours, it is practical to choose the pile plate method, which can be carried out during the same break. Methods with which pile plates can be constructed rapidly in one session or in a succession of suitably short periods are recommended. Methods requiring a break longer than 24 hours are suitable only for tracks with two or more rails. There is, however, an obvious need for further improvement of existing construction methods.Tämä työ on tehty Oy VR-Rata Ab:n Rautatiesuunnittelun georyhmässä. Työn on rahoittanut Ratahallintokeskus. Työn ohjauksen johtoryhmään on kuulunut asiantuntijoita Ratahallintokeskuksesta ja VR-Radan Rautatiesuunnittelun geo- ja siltaryhmistä. Tässä työssä tarkasteltiin pengerpaalurakenteita eli paaluhattualueita ja paalulaattoja. Työssä esiteltiin pengerpaalurakenteet yleisellä tasolla. Rakenteiden korjaamis- ja rakentamismenetelmiä tarkasteltiin erityisesti liikenteen alaisen raiteen näkökulmasta. Rautatieympäristö asettaa rakentamiselle erityisiä vaatimuksia. Rakentamisen nopeus ja jaksotus sopiviin raidevarauksiin on erityisen tärkeää. Rakentamiskustannusten lisäksi merkittävässä asemassa ovat liikennehaittakustannukset. Liikennehaittakustannuksiin vaikuttaa monet eri tekijät, joten niiden arvioiminen on haastavaa. Tavoitteena oli vertailla rakentamismenetelmiä ja esittää suosituksia kunkin menetelmän soveltuvuudesta liikenteen alaiselle raiteelle. Työn tavoitteena oli myös esittää ehdotuksia jatkotutkimuksen aiheeksi.